The Mock Turtle (Sir Michael Hordern), who says he is from what mock turtle soup is made, is a bull in a turtle's shell. This was because mock turtle soup (for those who couldn't afford to have real turtle soup) was generally made from veal.
Michael Crawford played his role at the same time as he was appearing in the West End comedy "No Sex Please, We're British". He would leave the studio in full make-up and remove it in the car on his way to the theatre.
The voice-over narrator at the opening says the time of year is early July, and Alice at the tea party says the day of the month is the 4th. It was on July 4, 1862, on a boating trip that Lewis Carroll first told the Alice's Adventures in Wonderland story to Alice Liddell and her two sisters.
Because of the film being barely released in the US, it fell into the public domain there after its 1985 US VHS release, meaning anyone in the US can make and sell a VHS/DVD of the film. Most budget releases of this film are duplicates of second- or third-generation sources in 1.33:1 pan and scan.
A dialogue scene was filmed between Alice (Fiona Fullerton) and The Cheshire Cat (Roy Kinnear), with the latter perched in a tree. Although some stills survived, the footage was cut from the final print, and may no longer exist.